Changelogs generation

[chevdor]

This PR introduces a script and some templates to use the prdoc involved in a release and build:

• the changelog
• a simple draft of audience documentation

Since the prdoc presence was enforced in the middle of the version 1.5.0, not all PRs did come with a prdoc file.
This PR creates all the missing prdoc files with some minimum content allowing to properly generate the changelog.
The generated content is not suitable for the audience documentation.

The audience documentation will be possible with the next version, when all PR come with a proper prdoc.

Assumptions

• the prdoc files for release vX.Y.Z have been moved under prdoc/X.Y.Z
• the changelog requires for now for the prdoc files to contain author + topic. Thos fields are optional.

The build script can be called as:

VERSION=X.Y.Z ./scripts/release/build-changelogs.sh

Related:

• Add PRdoc check #1408